Enterobacteriaceae Research Articles

COVID-19 Pandemic Modulates the Environmental Contamination Level of Enteric Bacteria from WWTPs

The COVID-19 pandemic was a challenge for the whole world, and it had major secondary effects on humans and environmental health. The viral infection induced, in many situations, secondary bacterial infections, especially enteric infections, by destabilizing the balance of the gastrointestinal microbiota. The large-scale use of antibiotics and biocides for both curative and preventive purposes has resulted in an increase in bacterial resistance, and at the same time, the possibility of pathogenic microorganism multiplication and their dissemination to natural environments. Wastewater is the main vector of fecal microorganisms that favors their dissemination into natural aquatic ecosystems. The present paper aims to analyze the effect of the COVID-19 pandemic on the microbiological quality of wastewater from sewage treatment plants in Romania and its impact on receiving rivers. In order to highlight different and important areas in Romania, three cities from the east, center and west were selected for a microbiological evaluation of their WWTP influents and effluents from the pre-COVID-19 period and during the COVID-19 pandemic peak period, when the COVID-19 pandemic had a direct impact on WWTP microbial compositions. Our study shows that a higher level of contamination with fecal bacteria is linked to a higher COVID-19 incidence. The increased usage of pharmaceutical compounds, in turn, increases the number of resistant bacteria reaching the environment via WWTP effluents.

Monitoring of Klebsiella pneumoniae as one of the criteria of microecological characterization of a water body

Introduction. Representatives of the family Enterobacteriaceae are ubiquitous in the environment, causing severe, including opportunistic diseases in immunocompromised individuals. The occurrence of antibiotic-sensitive bacteria of the Klebsiella genus within the recreational zone of a water body is potent of posing an epidemiologic danger to the inhabitants of the settlement. 
 Materials and Methods. Water samples from the surface aquifers of the Don and Temernik rivers of Rostov-on-Don served as the material for the study. The sensitivity of isolates of Kl. pneumoniae isolates to fourteen antibacterial preparations were investigated by disk-diffusion method in accordance with the requirements of MUK 4.2.1980-04 and EUCAST v. 13.0 (2023). 13.0 (2023). Carbapenemase genes VIM, IMP, NDM, KPC, OXA-48, NDM were determined using commercial diagnostic kits AmpliSense MDR MBL-FL, AmpliSense MDR KPC/OXA-48-FL, AmpliSense MDR Ab-OXA-FL.
 Results. In 2022, 247 isolates of Klebsiella pneumoniae were isolated in 14 biotopes of water bodies of Rostov-on-Don. Biotopes of epidemiological significance were identified with the presence of antibiotic resistance genes in 28 isolates isolated above and below the sewage discharge site (sampling point #1 and #5) and strains isolated from the mouth of the Temernik River (sampling point #14). Phenotype of multidrug-resistant (MDR) in point No. 1 possessed 22%, point No. 5 – 26.9%, point No. 14 – 26%; phenotype of extreme drug resistance (XDR) in point No. 1 possessed 11.1 %, point No. 5 – 15.3%, point No. 14 – 13%; phenotype of pan-drug-resistant (PDR) in point No. 1 did not possess, point No. 5 – 3.8%, point No. 14 – 4.3%.
 Limitations. A limitation of the study is related to the location of water sampling from the river. Don and R. Temernik on the territory of Rostov-on-Don, covering from March to November 2022. In this article, we limited ourselves to sanitary-bacteriological and molecular genetic analysis.
 Conclusion. The detection of PDR, XDR, and MDR antibiotic-resistant phenotypes of Klebsiella pneumoniae, as well as the detection of resistance genes, indicates to an increased risk of water-associated acute intestinal infections, especially in immunosuppressed individuals.

Hygienic status of beef butcher shop facilities and antibiotic resistance profile ofSalmonella enterica in Ethiopia.

The microbiological quality of meat is influenced by the conditions of hygiene prevailing during production and handling.Thus, thisstudy aimed to assess the prevalence ofSalmonella entericaand its antimicrobial resistance, load of hygiene indicator bacteria including E. coli(ECC), coliforms (CC), total coliform (TCC), Enterobacteriaceae(EB) and aerobic plate count (APC), and meat handler's food safety knowledge and hygiene practices in butcher shops in two cities, Addis Ababa and Hawassa in Ethiopia, during 2020 and 2021. A total of 360 samples of beef carcasses (n = 120), knives (n = 60), chopping boards (n = 60), weighing balance (n = 60), and personnel's hands (n = 60) were randomly collected for microbial analysis. Besides, 120 participants were selected to participate in a food safety knowledge and hygiene practices assessment. TheS. entericaisolates were identified by agglutination test followed by qPCR targeting invA gene. Phenotypic antimicrobial resistance profiles ofS. entericawere determined using disk diffusion assays as described in CLSI. TheECC, CC, TCC, EB, and APC populations were quantified by plating ontopetrifilmplates.A structured questionnaire was used to determine food safety knowledge and hygiene practices of participants. Overall prevalence of S. enterica was 16.7% (95% CI, 8.3-26.7) and location seems to have no effect (p = 0.806).Only 20% of the S. entericawere resistant to ampicillin and tetracycline. However, the majority (80%) ofS. entericaisolates were susceptible to the panel of 11 antimicrobials tested.The overall mean ± SD (log CFU/cm2) of ECC, CC, TCC, EB, and APCwere 4.31 ± 1.15; 4.61 ± 1.33; 4.77 ± 1.32; 4.59 ± 1.38 and 5.87 ± 1.52,respectively.No significant difference (p = 0.123) in E. coli contamination was observed between samples of beef carcasses and chopping boards. The EB contamination showed no significant difference (p > 0.05) among sample sources. The APC contamination levels on beef carcass were significantly higher (p > 0.05) than other sample sources. A total of 56% (95% CI: 46.7 - 65.0) of the participants had poor knowledge and 65% (95% CI: 56.7 - 73.3)had poor hygiene practices towards food safety. This study highlighted the poor hygiene status of butcher facilities with a potential risk of beef safety. Thus, appropriate food safety control strategies and inspection is needed at retail establishments.

A folate inhibitor exploits metabolic differences in Pseudomonas aeruginosa for narrow-spectrum targeting.

Pseudomonas aeruginosa is a leading cause of hospital-acquired infections for which the development of antibiotics is urgently needed. Unlike most enteric bacteria, P. aeruginosa lacks enzymes required to scavenge exogenous thymine. An appealing strategy to selectively target P. aeruginosa is to disrupt thymidine synthesis while providing exogenous thymine. However, known antibiotics that perturb thymidine synthesis are largely inactive against P. aeruginosa.Here we characterize fluorofolin, a dihydrofolate reductase (DHFR) inhibitor derived from Irresistin-16, that exhibits significant activity against P. aeruginosa in culture and in a mouse thigh infection model. Fluorofolin is active against a wide range of clinical P. aeruginosa isolates resistant to known antibiotics. Metabolomics and in vitro assays using purified folA confirm that fluorofolin inhibits P. aeruginosa DHFR. Importantly, in the presence of thymine supplementation, fluorofolin activity is selective for P. aeruginosa. Resistance to fluorofolin can emerge through overexpression of the efflux pumps MexCD-OprJ and MexEF-OprN, but these mutants also decrease pathogenesis. Our findings demonstrate how understanding species-specific genetic differences can enable selective targeting of important pathogens while revealing trade-offs between resistance and pathogenesis.

Vaccine-elicited IL-1R signaling results in Th17 TRM-mediated immunity

Lung tissue resident memory (TRM) cells are thought to play crucial roles in lung host defense. We have recently shown that immunization with the adjuvant LTA1 (derived from the A1 domain of E. coli heat labile toxin) admixed with OmpX from K. pneumoniae can elicit antigen specific lung Th17 TRM cells that provide serotype independent immunity to members of the Enterobacteriaceae family. However, the upstream requirements to generate these cells are unclear. Single-cell RNA-seq showed that vaccine-elicited Th17 TRM cells expressed high levels of IL-1R1, suggesting that IL-1 family members may be critical to generate these cells. Using a combination of genetic and antibody neutralization approaches, we show that Th17 TRM cells can be generated independent of caspase-1 but are compromised when IL-1α is neutralized. Moreover IL-1α could serve as a molecular adjuvant to generate lung Th17 TRM cells independent of LTA1. Taken together, these data suggest that IL-1α plays a major role in vaccine-mediated lung Th17 TRM generation.

Еffectiveness of immunocorrective therapy for frequently ill children

Introduction. All acute respiratory infections are characterized by damage to the mucous membrane of the respiratory tract, a decrease in local immune defense and a weakening of nonspecific protective factors.Aim. To characterize the clinical effectiveness of the use of the immunocorrective drug in frequently ill children.Materials and methods. The article assessed the microbiological spectrum of the rhinopharyngeal landscape in 65 children: 33 children took an immunocorrective drug in addition to conventional therapy – the main group; 32 children received conventional therapy (the comparison group), and also investigated the possibility of regulating their polypathogenic microbiota using topical bacterial lysates.Results and discussion. The result of the therapy was a clinical improvement characterized by the relief of pharyngoscopic signs of chronic tonsillitis in children while taking topical bacterial lysates in form of lozenges. Analysis of the microbiota of the oropharyngeal mucosa in the studied patients of both groups before the start of therapy revealed the species diversity of opportunistic flora, among which Streptococcus pyogenes, Staphylococcus aureus, the family Enterobacteriaceae and Candida albicans were identified in all patients in diagnostic significant titers of 105–1010. After treatment in the main group, the ratio of the microbiota of the nasopharynx significantly changed, stimulation of the production of local immunity components was noted, which was confirmed by a decrease in the intensity of contamination of microbiota with polypathogenic functions to diagnostically insignificant titers. When comparing the species composition of the microbiota in the studied groups after treatment with topical bacterial lysates, a statistically significant positive effect was found without additional use of antibacterial drugs.Conclusions. It has been shown that the immunocorrective drug eliminates pharyngoscopic signs of rhinopharyngeal dysbiosis in children who are often and long-term ill.

Phenotypic and Genotypic Detection of UV-induced Bacteriocin Production in Enteric Gram-Negative Rods and their Activity against Escherichia coli O157: H7

Background: Virulence and antibiotic resistance of bacterial pathogens are one of the most universal threats to public health care. 
 Materials: In this study, a total of two hundred and fifty-seven (257) enteric bacteria isolated from human rectal swabs and cattle dung were screened for production of low-toxic, high target-specific bactericidal macromolecule peptides (Bacteriocin) against strains of E. coli 0157: H7 using agar well diffusion method. The producer isolates were exposed to ultra-violet (UV) rays (UV 302nm and 254nm) for induction.
 Results: Out of the 257 isolates, 21 (8.1%) were active against E. coli 0157: H7 due to their constitutive bacteriocin, however, on the induction by UV ray; only 7 (2.1%) retained their potency for bacteriocin production. Three (42.9%) of seven isolates were randomly selected for genotypic screening (Col 28b (L) and Col K genes) because of their increased zone of inhibition (bioactive ability) after exposure to UV ray; the isolates also showed resistance to ≤ 2 classes of antibiotics and exhibited Gamma/alpha haemolysis.
 Conclusion: This study revealed Serratia marcescens in this work to possess an antimicrobial molecule of bacteriocinogenic type with possession of Col 28b gene.

Overexpression of lasB Gene in Klebsiella pneumoniae and its Effect on Biofilm Formation and Antibiotic Resistance

Background: Klebsiella pneumoniae is the second most frequent pathogenic bacterium in the Enterobacteriaceae family, after E. coli. It is also regarded as a major pathogen responsible for healthcare-associated infections around the world. Objective: To look at how overexpressing the elastase gene (lasB) in K. pneumoniae affects biofilm development and antibiotic resistance. Methods: 25 clinical isolates of K. pneumoniae were received from Baghdad's Chemistry Analysis Center (CAC) and re-identified using the Vitek-2 method. The microtiter plate was used to measure biofilm production with ELISA. The disc diffusion method was used in antibiotic sensitivity tests in accordance with the CLSI 2022 criteria. The PlasB plasmid was transformed into K. pneumoniae via electroporation. Results: Out of 25 isolates, 11 (44%), 11 (44%), and 3 (12%) produced strong, moderate, and weak biofilms, respectively. One strong biofilm producer (KA1) was chosen for further investigation. The lasB plasmid was successfully transformed into KA1, yielding the KA1 (plasB) isolate. KA1 (plasB) formed considerably fewer biofilms than KA1, and it was more susceptible to tetracycline, doxycycline, and amoxicillin-clavulanic acid than KA1. Furthermore, KA1 (plasB) has shown a significant decrease in ampicillin resistance and an increase in ciprofloxacin sensitivity, but no variations in susceptibility to levofloxacin, cefotaxime, piperacillin-tazobactam, amikacin, or erythromycin when compared to KA1. Conclusions: Overexpression of the elastase gene (plasB) has a major impact on biofilm development and antibiotic resistance in K. pneumoniae.

Causal relationship between gut microbiota and gastric cancer: A two‑sample Mendelian randomization analysis.

The gut microbiota is associated with GC; however, the causal association between the gut microbiota and GC remains to be determined. The aim of the present study was to investigate the causal association between gut microbiota and gastric cancer (GC) from the perspective of Mendelian randomization (MR). The present study performed MR analysis using summary statistics from a genome-wide association study of the gut microbiome and GC. Inverse-variance weighted, MR-Egger and weighted median methods were used to investigate the causal relationship between gut microbiota and GC. Heterogeneity tests were performed using Cochrane's Q statistic. Horizontal polytropy was detected using Mendelian Randomization Pleiotropy RESidual Sum and Outlier were eliminated. Estimates from MR indicated that nine gut microorganism remained stable with regard to acceptance of heterogeneity and sensitivity methods. Among them, the genera Prevotella 7, Roseburia and Ruminococcaceae UCG014 were associated with an increased risk of GC; by contrast, the family Enterobacteriaceae, the genera Allisonella, Lachnospiraceae FCS020, Ruminococcaceae UCG004 and Ruminococcaceae UCG009, and the order Enterobacteriales decreased the risk of GC development. The present study demonstrated the potential importance of modulating the abundance of gut microbiota for the prevention and treatment of GC.

Oxidized glutathione reverts carbapenem resistance in blaNDM-1-carrying Escherichia coli.

The emergence of drug-resistant Enterobacteriaceae carrying plasmid-mediated β-lactamase genes has become a significant threat to public health. Organisms in the Enterobacteriaceae family containing New Delhi metallo-β-lactamase‑1 (NDM-1) and its variants, which are capable of hydrolyzing nearly all β-lactam antibacterial agents, including carbapenems, are referred to as superbugs and distributed worldwide. Despite efforts over the past decade, the discovery of an NDM-1 inhibitor that can reach the clinic remains a challenge. Here, we identified oxidized glutathione (GSSG) as a metabolic biomarker for blaNDM-1 using a non-targeted metabolomics approach and demonstrated that GSSG supplementation could restore carbapenem susceptibility in Escherichia coli carrying blaNDM-1 in vitro and in vivo. We showed that exogenous GSSG promotes the bactericidal effects of carbapenems by interfering with intracellular redox homeostasis and inhibiting the expression of NDM-1 in drug-resistant E. coli. This study establishes a metabolomics-based strategy to potentiate metabolism-dependent antibiotic efficacy for the treatment of antibiotic-resistant bacteria.

Emerging Concerns: Prevalence of Antimicrobial Resistance in <i>Aeromonas</i> and <i>Escherichia coli</i> in Retail Fish from Ganges Delta's Diamond Harbour Region

The study investigated the prevalence of Aeromonas spp. and Escherichia coli, pathogens associated with diseases in both fish and humans, within retail market Labeo rohita and L. catla samples obtained from the Diamond Harbour region of the Ganges delta. The primary focus was to assess the potential risks posed by these bacteria in terms of antibiotic resistance. A total of 46 presumptive Aeromonas and 29 nos of E. coli strains were successfully isolated from the sampled retail market carps. Among the isolated aeromonads, A. sobriae (15) and A. hydrophila (13) were dominant. The study revealed that 70 strains, comprising 42 aeromonads and 28 Escherichia coli, exhibited multiple antibiotic resistance (MAR). Notably, a significantly higher percentage of MAR was observed in bacterial strains isolated during the monsoon season. Analysis of the antibiotic resistance profiles demonstrated a total of 43 distinct profiles among the isolated strains. The contamination of farmed carps, particularly with enteric bacteria such as Escherichia coli, emerged as a significant concern for consumers in retail markets. The high frequency of multiple antibiotic-resistant aeromonads and Escherichia coli in retail carps, coupled with their potential dissemination through the food chain, poses serious threats to consumer health. Importantly, this report is likely the inaugural documentation of antimicrobial resistance (AMR) in aquacultured fish in the Diamond Harbour region of West Bengal. Given its proximity to the Ganges delta, there is a pressing need for ongoing and systematic documentation to address and mitigate these emerging health risks.

Assessing the Microbial Contamination Levels in Milk Samples from Rural and Urban Areas: A Focus on Raisen and Bhopal Districts

AbstractThis study aimed to assess the level of microbial contamination in raw cow milk samples collected from farms in rural and urban regions of Raisen and Bhopal districts, Madhya Pradesh, India. Recent data are gathered to investigate the microbial quality of the milk samples directly, rather than relying on reported findings from other sources. The results reveal that both rural and urban milk samples exhibit significantly higher bacterial colony counts compared to acceptable limits for total viable count. The average total viable count for urban samples is 8.699 log CFU mL−1, with a standard deviation of 0.821 log CFU mL−1, using a sample size of 1 mL. Moreover, urban samples show a higher initial incubation count (8.728 ± 0.431 log CFU mL‐1), indicating potential unsanitary milk handling practices in urban areas. In contrast, rural milk samples demonstrate significantly lower bacterial counts (8.0778 ± 0.079 log CFU mL−1) and exhibit superior laboratory sanitization measures. Enteric bacteria such as Escherichia coli, Enterobacter species, Klebsiella species, and Shigella are found in both urban and rural milk samples after isolation. However, strains of bacterial culture specific to Pseudomonas and Salmonella species are exclusively detected in urban samples, suggesting a higher contamination level in urban areas compared to rural regions. These findings highlight the urgent need for improved milk production and handling practices in both rural and urban areas, particularly in urban settings where the contamination levels are found to be significantly higher. The results of this study contribute to the understanding of microbial quality in raw cow milk and emphasize the importance of implementing appropriate interventions to ensure the safety and quality of milk consumed by the population.

Emphysematous Osteomyelitis: Literature Review and a Case Report

Emphysematous osteomyelitis is a rare form of osteomyelitis characterized by the presence of intraosseous gas. It is caused by gas-forming organisms, most commonly being members of the Enterobacteriaceae family (particularly Escherichia coli) or anaerobes. Comorbidities such as diabetes mellitus, malignancy, alcohol abuse, Crohn’s disease, and other etiologies causing immune suppression, predispose to this condition. A prompt diagnosis of this potentially fatal condition is required to expedite early management. We present a patient diagnosed with multifocal emphysematous osteomyelitis involving the pelvic bones, left proximal femur, vertebral bodies, ribs, and clavicle caused by E. coli to highlight the unusual diffuse involvement by this rare disease. In addition, we reviewed 58 reported cases of emphysematous osteomyelitis including our case. Our purpose in revising all these cases was to observe any significant difference in outcome (if any exists in mortality) based on age, gender, causative organism, site of involvement, and treatment received. However, we could not observe any significant difference in outcome.

Screening of Potential Phytochemicals for the Identified Candidate Virulence Proteins in Enterobacter huaxiensis

ABSTRACT: Enterobacter huaxiensis, a novel gram-negative bacterium of the family Enterobacteriaceae, was recovered from the blood of the patients at West China Hospital. The present study aims to predict potential lead molecules against the identified virulence-associated antibiotic-resistant protein for drug designing. Two virulence-associated antibiotic-resistance proteins belonging to the OqxAB efflux protein family of the RND superfamily were identified in the pathogen using bioinformatics tools/databases. Based on the structure prediction by homology modeling and validations, the RND transporter permease subunit, OqxB was selected as the potential target for lead identification. The binding pocket of the target protein was calculated using CASTp. A total of 204 phytochemicals were screened virtually to obtain compounds that had better binding affinity, drug-likeness and pharmacokinetic potential to be used as safe ligands against the target protein. Among these, Chrysoeriol, Isopimaric acid, Baicalein and Biochanin A were found to be within the permissible range of Lipinski rule of five for drug-likeness, possessing better ADMET properties, and lower target-protein binding energy (less than -8.0 kcal/mol). Ligand-protein docking showed stable non-covalent interactions between active site residues and ligands. Thus, these compounds may be considered potential inhibitors of the target protein that may inactivate the efflux pump and restore antibiotic sensitivity.

Physicochemical and bacteriological assessment of the polyethene packaged sachet water (popularly called “pure water”) as a major source of drinking water in Sagamu, Ogun State, Southwest, Nigeria

This study aimed to evaluate the physicochemical and bacteriological characteristics of polyethylene-packaged sachet water, commonly known as "pure water," produced and distributed in the Sagamu local government area of Ogun State, Southwest Nigeria. The research involved analyzing sachet water samples from various producers, sources, and distributors to assess their quality. Samples were collected randomly from six different locations/towns within Sagamu Local Government and subjected to physicochemical and bacteriological analysis. The findings were compared with the permissible limits established by reputable organizations such as WHO, EPA, Canada, and NIS. The results indicated that most parameters fell within the acceptable range set by WHO, EPA, Canada, and NIS. However, the pH levels of the sachet water samples (ranging from 4.73 to 6.10) were found to be acidic, deviating from the expected range of 6.5 to 10.5. Additionally, while the Total Heterotrophic Bacteria count and Enteric Bacteria count were slightly lower than the permissible limits, with Total Enteric Bacteria ranging from 300 to 480 cfu/100ml (permissible limit <500cfu/100ml) and Enteric Bacteria ranging from 280 to 380 cfu/100ml. Recommendations derived from the study include advocating for water-producing industries to establish their raw water sources in contamination-free zones, encouraging the involvement of well-equipped private and government hospitals in monitoring and reporting on the water quality of packaging industries, promoting the provision of safe piped water by credible individuals within communities, and emphasizing the role of regulatory bodies like SON and NAFDAC in continuously assessing the production and packaging standards of drinking water across communities.

Degradation and molecular docking of Curli to scout aggregation complexion

Curli, an extracellular protein fibril produced by certain gram-negative enteric bacteria, is responsible for neuro-degenerative diseases due to spontaneous misfolding of soluble proteins. This study investigates the effect of denaturing agents (Urea, Guanidine Hydrochloride) and varying pH (2–11) on the conformation of Curli protein, isolated from E. coli PHL628, due to changes in the external environment. The study focuses on the changing dynamics of the protein using intrinsic fluorescence property, UV-absorption, fluorescence anisotropic measurements, and extrinsic fluorescence property with the help of interaction with 1-anilinonaphthalene-8-sulphonate (ANS). The data showed that the absorption maximum (λmax) of protein was altered in variation of denaturant concentration and buffer pH. Molecular docking results revealed the interaction of Curli with Urea and GdnHCl, by comparing structural changes. This study determines how denaturants and changes in the external environment cause denaturation or modification in the folded structure of Curli protein and provides insight into binding sites of Curli with denaturants.

Molecular characteristics of carbapenem-resistant Enterobacteriaceae isolated from two tertiary hospitals in the Philippines

Species belonging to the family Enterobacteriaceae cause infections that result in clinically significant morbidity and mortality. These organisms have been shown to harbor multiple mechanisms of resistance to antibiotics, including carbapenems. Molecular characterization of resistance to carbapenems is critical since few effective therapeutic options exist, most of which are difficult to access in resource-limited settings. One hundred twenty-six Enterobacteriaceae isolates with phenotypic resistance to at least one carbapenem were collected from two tertiary hospitals in the Philippines from 2014 to 2016. The organisms were screened for the presence of genes coding for carbapenemases and extended spectrum β-lactamases (ESBLs) using multiplex PCR. Multilocus sequence typing (MLST) was performed for Klebsiella pneumoniae, Escherichia coli and Enterobacter cloacae complex. The majority of the carbapenem-resistant isolates were K. pneumoniae (70/126, 55.5%) followed by K. ozaenae (19/126, 15%). Amplification of genes conferring carbapenem resistance showed blaNDM in 89 isolates (70%), followed by blaKPC in 21 isolates (16%). MLST revealed the presence of different clones including ST16 (5/70), ST17 (3/70) and ST147 (9/70) in K. pneumoniae, and ST10 (3/13) in E. coli. This study shows that blaNDM is the most prevalent carbapenemase type among carbapenem-resistant Enterobacteriaceae (CRE). Presence of carbapenemase gene and multiple ESBLs in the same organism pose a risk in the clinical setting since it could confer higher antibiotic resistance. This high rate of resistance poses the risk of spread since it can be transferred by mobile genetic elements. This study illustrates the acute need for effective therapeutic and hospital infection controls against CREs.

Modeling the mosaic structure of bacterial genomes to infer their evolutionary history

The chronology and phylogeny of bacterial evolution are difficult to reconstruct due to a scarce fossil record. The analysis of bacterial genomes remains challenging because of large sequence divergence, the plasticity of bacterial genomes due to frequent gene loss, horizontal gene transfer, and differences in selective pressure from one locus to another. Therefore, taking advantage of the rich and rapidly accumulating genomic data requires accurate modeling of genome evolution. An important technical consideration is that loci with high effective mutation rates may diverge beyond the detection limit of the alignment algorithms used, biasing the genome-wide divergence estimates toward smaller divergences. In this article, we propose a novel method to gain insight into bacterial evolution based on statistical properties of genome comparisons. We find that the length distribution of sequence matches is shaped by the effective mutation rates of different loci, by the horizontal transfers, and by the aligner sensitivity. Based on these inputs, we build a model and show that it accounts for the empirically observed distributions, taking the Enterobacteriaceae family as an example. Our method allows to distinguish segments of vertical and horizontal origins and to estimate the time divergence and exchange rate between any pair of taxa from genome-wide alignments. Based on the estimated time divergences, we construct a time-calibrated phylogenetic tree to demonstrate the accuracy of the method.

Characterization of Langra Mango Peel Powder and Assessment of Its Prebiotic and Antioxidant Potential

The possibility of developing waste by-products of food processing into functional food additives along with probiotics is an interesting avenue to research. This study investigated the nutritional and functional attributes of dried mango peel powder (MPP) of Langra cultivar and its putative potential to act as a prebiotic in the presence of two probiotic strains Lacticaseibacillus rhamnosus NCDC347 and Limosilactobacillus fermentum NCDC143 @ 2.5 & 5% after 24 to 48 h fermentation. Proximate analysis revealed that the MPP contains 6.45 % moisture, 6.34 % protein, 3.88 % fat, 2.50 % ash, 32.86 % crude dietary fiber, and 47.97 % of total carbohydrate content. MP displayed substantial antioxidant potential with 54.6% DPPH inhibitory activity, 15.67 mg GAE/g TPC, 8.88 mg QuE/g TFC, OHC of 1.47 g oil/g, and a WHC of 4.7 g water/g. MPP could selectively stimulate the growth of two probiotic strains over enteric bacteria. It was revealed that a combination of MPP @5% with L. fermentum NCDC143 after 24 h fermentation had the best in vitro prebiotic activity score of 3.35 and 3.53 against Escherichia coli ATCC 25922 and Enterococcus faecalis NCDC114, respectively. The prebiotic activity score of MPP was better than commercial prebiotic malto-dextrin for all combinations of probiotic and enteric strains tested. The percentage DPPH inhibition activity of MPP increased during fermentation with L. fermentum NCDC143, highlighting its role as a source of antioxidants. These findings contribute to the formulation of synbiotic products that are able to maintain selected healthy microbiota in the human gut.

Sanitation in urban areas may limit the spread of antimicrobial resistance via flies.

Synanthropic filth flies are common where sanitation is poor and fecal wastes are accessible to them. These flies have been proposed as mechanical vectors for the localized transport of fecal microbes including antimicrobial resistant (AMR) organisms and associated antimicrobial resistance genes (ARGs), increasing exposure risks. We evaluated whether an onsite sanitation intervention in Maputo, Mozambique reduced the concentration of enteric bacteria and the frequency of detection of ARGs carried by flies collected in household compounds of low-income neighborhoods. Additionally, we assessed the phenotypic resistance profile of Enterobacteriaceae isolates recovered from flies during the pre-intervention phase. After fly enumeration at study compounds, quantitative polymerase chain reaction was used to quantify an enteric 16S rRNA gene (i.e., specific to a cluster of phylotypes corresponding to 5% of the human fecal microflora), 28 ARGs, and Kirby Bauer Disk Diffusion of Enterobacteriaceae isolates was utilized to assess resistance to eleven clinically relevant antibiotics. The intervention was associated with a 1.5 log10 reduction (95% confidence interval: -0.73, -2.3) in the concentration of the enteric 16S gene and a 31% reduction (adjusted prevalence ratio = 0.69, [0.52, 0.92]) in the mean number of ARGs per fly compared to a control group with poor sanitation. This protective effect was consistent across the six ARG classes that we detected. Enterobacteriaceae isolates-only from the pre-intervention phase-were resistant to a mean of 3.4 antibiotics out of the eleven assessed. Improving onsite sanitation infrastructure in low-income informal settlements may help reduce fly-mediated transmission of enteric bacteria and the ARGs carried by them.